1. Field of the Invention
This invention relates to an image scanner and, more particularly, to an apparatus and method for accurately determining the actual sheet size (area) of a print medium, by which sheets smaller than standard size can be scanned using a sheet carrier.
2. Discussion of Related Art
Along with recent trends in multimedia technology, common computer peripheral devices, e.g., printers, have begun to incorporate facsimile and scanner functions into desktop computer systems. Meanwhile, it is often desired to process the images of non-standard size sheets of print medium such as a business card or photograph.
In scanning images printed on sheets of print medium below A4 size, the scanning area beyond the print medium's boundaries is typically either a white (reference) panel or a black panel such as a sheet carrier or other opaque mechanical structure. The white panel, however, routinely becomes contaminated with ink during the printing operation, so that the scanning of these areas is merely bypassed and the unscanned area is processed as free data. Thus, the white panel is rendered ineffective as a background.
The black panel (or blank area of a sheet carrier), on the other hand, is regarded as image data and scanned normally, resulting in the processing of useless data. This unnecessarily increases the scanning time, while placing undue data storage requirements on the scanner's hardware and slowing any subsequent image data processing.
U.S. Pat. Nos. 5,699,165 and 5,060,281 have disclosed scanner technologies aimed at solving these problems. Neither of these references, however, satisfy current industry needs.
SUMMARY OF THE INVENTION
Accordingly, in order to overcome such drawbacks in the conventional art, it is therefore an object of the present invention to provide a scanning method in which scanning time is reduced when scanning relatively small (i.e., less than maximum size) sheets of print medium, e.g., paper.
It is another object of the present invention to provide a scanning method which reduces the amount of data to be scanned, when scanning relatively small (i.e., less than maximum size) sheets of print medium, e.g., paper.
It is yet another object of the present invention to provide an apparatus for realizing the above scanning method.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a sheet-size-determining device in a scanner, having a sheet carrier, with a pattern formed across the entire surface thereof, for holding a sheet of printed medium; a paper feeding device for controlling the feeding operation of the sheet carrier; a shuttle scanner module for scanning image data of the sheet of printed medium and outputting the scanned image data; a carriage return motor for driving the shuttle scanner module; an image memory for temporarily storing the scanned image data output from the shuttle scanner module; and a controller for analyzing the temporarily stored image data and outputting a control signal to the carriage return motor according to the analysis.
According to another aspect of the present invention, there is also provided a method for determining the sheet size of a print medium, having the steps of: scanning a block of the print medium using a shuttle scanning module; temporarily storing the scanned block in an image memory; analyzing the stored block in order to recognize a pattern within the scanned block; and limiting an operating range of the shuttle scanner module if a pattern is recognized in the analyzing step.